Vehicle drive/suspension system

ABSTRACT

One aspect of the invention is directed to a vehicle drive/suspension system including a chassis having a front portion, a rear portion and a pair of sides; a drive axle having opposed end portions extending between said sides; an elongated rocker arm, having opposed end portions, connected to each of said opposed end portions of said drive axle and pivotally mounted to each of said sides substantially at said opposed end portions of said drive axle; a sprocket rotatably fixed to each of said opposed end portions of said rocker arms; a rotatable drive sprocket connected to each of said opposed end portions of said drive axle; and a drive link for each rocker arm connected to rotate said sprockets in conjunction with said drive sprockets.

FIELD OF THE INVENTION

[0001] This invention relates to a vehicle drive/suspension system,particularly to a drive/suspension system for four-wheel driveall-terrain/utility type vehicles.

BACKGROUND OF THE INVENTION

[0002] All-terrain/utility type vehicles are known in the art and havebeen utilized for many years. Typical of these types of vehicles areGator® utility vehicles manufactured by John Deere Company and“Groundforce 100” manufactured by CheTech Company. Such vehicles have awide variety of applications including industrial, governmental andprivate uses. Such vehicles have historically required heavy dutyconstruction, the ability to negotiate rough terrain, ability to haulheavy loads, provide high ground clearance and provide a safe, reliablevehicle for the operator and, typically, at least one passenger.

[0003] Recently, there has been a trend toward more frequent use of suchvehicles under circumstances wherein they traverse ground or terrainthat should not be disturbed or broken. Typical uses include landscapingand/or maintaining lawns or the grounds of office parks, etc. and golfcourses, for example. Such uses oftentimes require that the turfunderfoot not be disturbed or “scuffed.” Also, such uses often requireoperation in tight spaces that require comparatively tight turns, whichexacerbates turf “scuffing.”

[0004] Prior vehicles have tended to disturb the grounds such as by turf“scuffing” or destruction of the ground underfoot. This phenomenon hasespecially been a problem with respect to scuffing during turning ofsuch all-terrain/utility type vehicles, especially four-wheel drivevehicles since they tend to disturb the turf much in the same way astreads on a military tank. This is especially important in relation tosix-wheeled vehicles because the front wheels are not powered (as in a4×4 vehicle), the front wheels do not contribute to turf “scuffing.”However, the effect of the four rear drive wheels is exacerbated.

[0005] Safety is also an important issue in six- or eight-wheeledvehicles with axles mounted rigidly to the frame. This is clearlyillustrated when such a vehicle climbs the crest of a hill or gully. Thefront wheels continue to climb, loosing contact with the ground untilthe vehicle progresses far enough that the center of gravity shifts andthe vehicle “teeters”, slamming down on the front wheels (the rearwheels coming off the ground in the process), much like a trackedvehicle would be expected to perform. Accordingly, it has been alongstanding desire to manufacture an all-terrain/utility type vehiclethat is capable of meeting the traditional requirements of such vehiclesbut also provide operator safety, high ground clearance, facilitate easeof turning and reduce and/or eliminate turf “scuffing.”

SUMMARY OF THE INVENTION

[0006] One aspect of the invention is directed to a vehicledrive/suspension system including a chassis having a front portion, arear portion and a pair of sides; a drive axle having opposed endportions extending between said sides; an elongated rocker arm, havingopposed end portions, connected to each of said opposed end portions ofsaid drive axle and pivotally mounted to each of said sidessubstantially at said opposed end portions of said drive axle; asprocket rotatably fixed to each of said opposed end portions of saidrocker arms; a rotatable drive sprocket connected to each of saidopposed end portions of said drive axle; and a drive link for eachrocker arm connected to rotate said sprockets in conjunction with saiddrive sprockets.

[0007] Another aspect of the invention is directed to a vehicledrive/suspension system including a chassis having a front portion, arear portion and a pair of sides; a drive axle having opposed endportions extending between said sides; an elongated rocker arm havingopposed end portions and a pivot point pivotally mounted to each of saidsides at said pivot points and connected to said opposed end portions ofsaid drive axle, said pivot points being located at positions other thanmiddle points along the length of said rocker arms; a sprocket rotatablyfixed to each of said opposed end portions of said rocker arms; arotatable drive sprocket connected to each of said opposed end portionsof said drive axle; and a drive link for each rocker arm connected torotate said sprockets in conjunction with said drive sprocket.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a bottom plan view of portions of a drive/suspensionsystem in accordance with aspects of the invention.

[0009]FIG. 2 is a perspective view of the drive/suspension system shownin FIG. 1 taken from the rear and above.

[0010]FIG. 3 is a perspective view of the drive/suspension system fromFIG. 1 shown from the rear and below.

[0011]FIG. 4 is a perspective view of the drive/suspension system shownin FIG. 1 from the rear and below and further showing a drive chainutilized in accordance with aspects of the invention.

[0012]FIG. 5 is a side elevational view of the drive/suspension systemfrom FIG. 1.

[0013]FIG. 6 is a perspective view of a portion of a chassis taken fromthe drive/suspension system in accordance with the invention.

[0014]FIG. 7 is a perspective view of a drive axle in accordance withaspects of the invention having several parts broken away for ease ofunderstanding.

[0015]FIG. 8 is a perspective view of a rocker arm in accordance withaspects of the invention.

[0016]FIG. 9 is a perspective view of a pivot pin utilized in accordancewith aspects of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] It will be appreciated that the following description is intendedto refer to specific embodiments of the invention selected forillustration in the drawings and is not intended to define or limit theinvention other than in the appended claims.

[0018] Referring now to the drawings generally, a vehicledrive/suspension system 10 is shown. Chassis 12 includes sides 14 and16, rear-cross member 18 which generally defines a rear portion, and amiddle-cross member 20. No front cross portion is shown. However, afront-cross member is typically included at the front portion. Forexample, a steering axle is typically mounted to the front of thevehicle chassis. Such front wheels would not typically be drive wheels.A drive axle 22 connects between sides 14 and 16. Drive axle 22 includesan axle housing 24 and an elongated axle shaft 26 having opposedportions 28 and 30. Affixed to axle shaft 26 are a pair of drivesprockets 32 and 34. A pair of brakes 36 and 38 are also mounted to axleshaft 26 inwardly of drive sprockets 32 and 34. Preferably, brakes 36and 38 are drum type brakes, although they can be other types of brakessuch as disc brakes and the like.

[0019] Axle housing 24 contains typical gear apparatus well known in theart and not described herein that connects to universal joint 40 which,in turn, connects to a drive shaft (not shown).

[0020] It should be understood that the axle is not limited to beingdriven by a coupled drive shaft as shown. For example, it may also bedriven by a belt-engaged torque converter clutch. The drawings show anaxle with a universal joint 40 for simplicity of illustration. Differentaxles may be used such as an axle with a stub shaft that a driventorque-converter clutch is mounted to. There may also be an additionalmounting point between the axle and the chassis to help stabilization.

[0021] As best shown in FIGS. 5 and 6, a pair of mounting plates 42 and44 are affixed to each of side rails 14 and 16 and extend downwardlytoward elongated rocker arms 46 and 48.

[0022] The rocker arms 46 and 48 have opposed end portions 50 and 52 anda center point 54, which is equidistant between the opposed end portions50 and 52. Each opposed end portion 50 and 52 connects to a sealedbearing housing 56. The sealed bearing houses 56 have axles 58 ontowhich wheels (not shown) may be mounted.

[0023] On each inboard end of axle 58 is mounted a sprocket 60 to whichdrive chains 62 as shown in FIG. 4 are connected. Each pair of sprockets60 on rocker arms 46 and 48 is linked to corresponding drive sprockets32 and 34. Tension sprockets 62 and 64 are slidably mounted onto rockerarms 46 and 48, respectively. Tension sprockets 62 and 64 may beutilized to facilitate changing of chains 62.

[0024] A dampener 66 in the form of a shock absorber connects betweeneach of the rocker arms 46 and 48 and chassis 12 by a connection 68mounted on cross member 20. Connectors 68 are best shown in FIG. 6.

[0025] Rubber stops 70 are mounted to the underside of side rails 14 and16 at the rearward portion of chassis 12 and are positioned in alignmentwith rocker arms 46 and 48. Rubber stop members 70 prevent rocker arms46 and 48 from pivoting upwardly and into contact with side rails 14 and16, respectively.

[0026] As best shown in FIGS. 3 and 8, rocker arms 46 and 48 have pivotmounts 72 and 74. Each pivot mount is comprised of a pair of upwardlyextending plates 76 and 78 extending upwardly therefrom and include asealed bearing housing 80. Sealed bearing housing 80 is aligned with thecentral axis of axle shaft 26 and openings 82 and 84 in mounting plates42 and 44 such that rocker pin 86 extends through mounting plate 44,mounting plate 76, sealed bearing housing 80, mounting plate 78 andthrough the opening in axle shaft 26. The threads 88 of rocker pin 86engage nut 90 that is welded to mounting plate 42 to secure the rockerarms 46 and 48 to chassis 12 and drive axle 22.

[0027] Although pivot member 72 may be mounted at substantially anyposition along elongated rocker arms 46 and 48, it is highlyadvantageous and especially preferred that mounting member 72 be mountedat a position removed or away from center point 54. Mounting the pivotmount away from center point 54 causes a “preloading” of either thefront portion or rear portion of the vehicle in which the system isinstalled, thereby reducing the load distribution on either the front orrear wheels associated with the system (not necessarily the vehicle,depending on the number of wheels). This, in turn, assists in reducingturf “scuffing”, especially during turning. Also, such preloading easesthe act of turning the vehicle from the operator's standpoint. It isespecially preferred to have preloading in the range of about 55-65% ofthe load distribution to the rear of the system/vehicle, especiallyabout a 60% preloading.

[0028] In operation, a vehicle utilizing the drive/suspension system ofthe invention can provide all of the additional requirements ofall-terrain/utility type vehicles and also achieves a surprising degreeof ability to reduce turf scuffing, ease turning of the vehicle andprovide improved ground clearance for enhanced operation of the vehicle.Application of power from any type of drive device such as gasolineengine, diesel engine, electric motor or the like is transferred throughthe drive shaft (not shown) to universal joint 40 and into the gearsystem in axle housing 24. Driving motion is transmitted through axleshaft 26 toward drive sprockets 32 and 34. Further drive action istransmitted through chain 62 to sprockets 60, through axles 58 and tothe wheels (not shown). Reduction between the engine shaft and thewheels is preferably achieved within the gear reduction of axle housing24. Additional reduction can be achieved by utilizing different-sizedsprockets 60 in comparison to other drive sprockets 32 and 34.Preferably, there is about a 5% reduction between the sets of sprockets.

[0029] The unique drive/suspension system of the invention allowsall-terrain/utility type vehicles to avoid traditional suspensionsystems based on leaf springs, coil springs, shock absorbers or the likeas typically configured. The resulting structure is far stronger andless subject to inordinate wear, yet provides a comparatively soft ridefor the cargo and/or passengers by virtue of the utilization of thedampers 66.

[0030] Use of the drive/suspension system of the invention in asix-wheeled vehicle is especially advantageous. Its advantages are indirect relation to other six-wheeled vehicles, wherein either one orboth of the rear drive axles are rigid to the frame. The advantage tothe invention system is that all four drive wheels have an independentaction to the chassis, thereby providing 1) consistent traction inuneven terrain by allowing all four wheels to engage the ground at alltimes, and 2) a smoother ride to the passengers since the floating axlesaverage out a lot of the bumps in the terrain (for example, driving overa 6″ diameter log only raises the chassis about 3″, due to the ratio ofthe pivot arms.

[0031] Although this invention has been described in connection withspecific forms thereof, it will be appreciated that a wide variety ofequivalents may be substituted for the specific elements describedherein without departing from the spirit and scope of the invention asdescribed in the appended claims. For example, although a drive chain 62having openings sized and shaped to receive teeth has been shown inconjunction with sprockets 32, 34, 60, 62 and 64, all having teeth,other components may be used. As an example, a pulley and belt systemcan be used as well as any number of other drive/linking systems knownin the art. Thus, although the term “sprocket” is used herein to referto use of such sprockets with teeth, its definition is sufficientlybroad to cover other configurations, constructions and components suchas the aforementioned pulleys and the like so long as the component isrotatable and capable of engaging a drive belt, chain or link of sometype.

[0032] Also, although gas/piston type shock absorbers utilized asdampeners 66 are shown as the preferred embodiment, other types ofdampeners may be used. For example, coil springs or similar devices maybe used.

What is claimed is:
 1. A vehicle drive/suspension system comprising: achassis having a front portion, a rear portion and a pair of sides; adrive axle having opposed end portions extending between said sides; anelongated rocker arm, having opposed end portions, connected to each ofsaid opposed end portions of said drive axle and pivotally mounted toeach of said sides substantially at said opposed end portions of saiddrive axle; a sprocket rotatably fixed to each of said opposed endportions of said rocker arms; a rotatable drive sprocket connected toeach of said opposed end portions of said drive axle; and a drive linkfor each rocker arm connected to rotate said sprockets in conjunctionwith said drive sprockets.
 2. The vehicle of claim 1 further comprisinga dampener connected between an opposed end portion of each of saidrocker arms and said chassis.
 3. The vehicle of claim 2 wherein saiddampeners are shock absorbers.
 4. The vehicle of claim 1 furthercomprising a brake associated with each of said drive sprockets.
 5. Thevehicle of claim 1 further comprising a tension sprocket mounted on eachof said rocker arms and connected to said drive link.
 6. The vehicle ofclaim 5 wherein said tension sprockets are slidably fixed to said rockerarms.
 7. The vehicle of claim 1 further comprising a rubber stop membermounted on each side of said chassis and in alignment with correspondingones of said rocker arms.
 8. The vehicle of claim 1 further comprisingi) a pivot plate extending from said chassis toward said drive axle, ii)a pivot mount associated with each of said rocker arms and iii) a pivotpin extending through each of said pivot mounts, corresponding ones ofsaid pivot plates and into corresponding ones of said opposed endportions of said drive axle.
 9. The vehicle of claim 8 wherein saidpivot pins threadingly engage said opposed end portions of said driveaxle.
 10. The vehicle of claim 1 wherein each of said rocker arms has amiddle point located equidistant from ends thereof and wherein saidrocker arms are pivotally mounted to said opposed end portions of saiddrive axle at locations away from said middle points.
 11. The vehicle ofclaim 10 wherein said rocker arms are pivotally mounted at locationsthat cause about 55-65% of the weight of said system to be biased towardsaid rear portion.
 12. The vehicle of claim 1 wherein said drive axle ispositioned below said sides.
 13. The vehicle of claim 1 wherein saiddrive link is a chain or a belt.
 14. A vehicle drive/suspension systemcomprising: a chassis having a front portion, a rear portion and a pairof sides; a drive axle having opposed end portions extending betweensaid sides; an elongated rocker arm, having opposed end portions and apivot point, pivotally mounted to each of said sides at said pivotpoints and connected to said opposed end portions of said drive axle,said pivot points being located at positions other than middle pointsalong the length of said rocker arms; a sprocket rotatably fixed to eachof said opposed end portions of said rocker arms; a rotatable drivesprocket connected to each of said opposed end portions of said driveaxle; and a drive link for each rocker arm connected to rotate saidsprockets in conjunction with said drive sprockets.
 15. The vehicle ofclaim 14 further comprising a dampener connected between an opposed endportion of each of said rocker arms and said chassis.
 16. The vehicle ofclaim 15 wherein said dampeners are shock absorbers.
 17. The vehicle ofclaim 14 further comprising a brake associated with each of said drivesprockets.
 18. The vehicle of claim 14 further comprising a tensionsprocket mounted on each of said rocker arms and connected to said drivelink.
 19. The vehicle of claim 18 wherein said tension sprockets areslidably fixed to said rocker arms.
 20. The vehicle of claim 14 furthercomprising a rubber stop member mounted on each side of said chassis andin alignment with corresponding ones of said rocker arms.
 21. Thevehicle of claim 14 further comprising i) a pivot plate extending fromsaid chassis toward said drive axle, ii) a pivot mount associated witheach of said rocker arms and iii) a pivot pin extending through each ofsaid pivot mounts, corresponding ones of said pivot plates and intocorresponding ones of said opposed end portions of said drive axle. 22.The vehicle of claim 21 wherein said pivot pins threadingly engage saidopposed end portions of said drive axle.
 23. The vehicle of claim 14wherein said rocker arms are pivotally mounted at locations that causeabout 55-65% of the weight of said system to be biased toward said rearportion.
 24. The vehicle of claim 14 wherein said drive axle ispositioned below said sides.
 25. The vehicle of claim 14 wherein saiddrive link is a chain or a belt.